Power storage device and method for producing power storage device

Abstract

The present invention comprises an electrode assembly (14) in which a positive electrode plate (11) and a negative electrode plate (12) are wound with a separator (13) interposed therebetween. The positive electrode plate (11) includes: a positive electrode core (30); a positive electrode mixture layer (32) formed on the surface of the positive electrode core (30); and a first exposed part (34) where the positive electrode core (30) is exposed. The first exposed part (34) is provided at the upper end in the winding axis direction of the electrode assembly (14). The first exposed part (34) has formed therein a plurality of notch sections (34A) which are arranged in the winding direction of the electrode assembly (14). The notch sections (34A) each have a first end, which is located on the edge side of the first exposed part (34), and a second end, which is located on the first mixture layer side of the first exposed part (34), and are formed inclined at a prescribed angle θ in the winding axis direction. In the first exposed part (34), the second end is located closer to the end of the first exposed part than the first end in the winding direction.

Description

Electricity storage device and method for manufacturing the same

[0001] The present disclosure relates to an electricity storage device and a method for manufacturing an electricity storage device.

[0002] Electricity storage devices such as cylindrical secondary batteries are known. The electricity storage device includes an electrode assembly in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween. A tabless structure for an electricity storage device is also known (see, for example, Patent Document 1). The tabless structure is a structure in which the positive electrode tab or the negative electrode tab is eliminated from the electrode assembly. The tabless structure can achieve low resistance for the electricity storage device. Furthermore, in the tabless structure, a configuration in which the exposed portion joined to the current collector is folded is known. This allows the proportion of the mixture layer in the electrode assembly to be increased. As a result, the capacity of the electricity storage device can be increased.

[0003] Special Publication No. 2022-512776

[0004] In recent years, power storage devices have been required to be used in harsher environments and conditions, and there is a demand for improving the reliability of power storage devices.

[0005] Therefore, an object of the present disclosure is to provide a power storage device and a method for manufacturing a power storage device that can improve reliability.

[0006] The energy storage device according to the present disclosure comprises an electrode body in which a first electrode plate and a second electrode plate are wound with a separator interposed therebetween, and the first electrode plate includes a first core, a first mixture layer formed on the surface of the first core, and a first exposed portion where the first core is exposed, and the first exposed portion is provided at one end of the electrode body in the winding axis direction, and a plurality of notches are formed in the first exposed portion and aligned in the winding direction of the electrode body, and the notches each have a first end on the edge side of the first exposed portion and a second end on the first mixture layer side, and are formed at an angle in the winding axis direction, and the second end of the first exposed portion is closer to the end of the first exposed portion in the winding direction than the first end.

[0007] The manufacturing method for an energy storage device according to the present disclosure is a manufacturing method for an energy storage device comprising an electrode body in which a first electrode plate and a second electrode plate are wound with a separator interposed therebetween, the first electrode plate including a first core and a first composite layer formed on the surface of the first core, a first exposed portion where the first core is exposed is provided at one end of the electrode body in the direction of the winding axis, a plurality of notches are formed in the first exposed portion, the notches are formed at an angle relative to the direction of the winding axis, strip portions are formed between adjacent notches, and the strip portions are folded, wherein when the strip portions are folded, the strip portions are pushed down by a folding jig, and the folding jig has a first sphere that pushes down the strip portions.

[0008] According to the power storage device and the method for manufacturing the power storage device of the present disclosure, reliability can be improved.

[0009] Fig. 1 is a cross-sectional view along the axial direction showing an electric storage device according to an example of an embodiment; Fig. 2 is a schematic diagram showing a positive electrode plate unfolded; Fig. 3 is a plan view of an electrode body; Fig. 4 is a flow diagram showing a manufacturing process of an electric storage device according to an example of an embodiment; Fig. 5 is a schematic diagram showing a folding process; Fig. 6 is a plan view of an electrode body showing a moving path of a folding jig in the folding process;

[0010] An example of an embodiment of the present disclosure will be described in detail below. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for facilitating understanding of the present disclosure, and can be appropriately changed according to the application, purpose, specifications, etc.

[0011] [Electricity Storage Device] An electric power storage device 10 as an example of an embodiment will be described with reference to FIG.

[0012] The power storage device 10 is, for example, a cylindrical secondary battery. The power storage device 10 includes a wound electrode assembly 14, a non-aqueous electrolyte (not shown), a cylindrical metal outer can 15 with a bottom that houses the electrode assembly 14 and the non-aqueous electrolyte, and a sealing body 16 that closes the opening of the outer can 15.

[0013] The electrode assembly 14 has a wound structure in which a strip-shaped positive electrode plate 11 and a strip-shaped negative electrode plate 12 are wound with two strip-shaped separators 13 interposed therebetween. In addition, in the winding axis direction, the positive electrode plate 11 protrudes upward relative to the negative electrode plate 12 and the separator 13, and the negative electrode plate 12 protrudes downward relative to the positive electrode plate 11 and the separator 13. The positive electrode plate 11 has a first exposed portion 34 in which the positive electrode mixture layer 32 is not provided and the positive electrode core 30 is exposed, at the upper end in the width direction from the winding start end to the winding end end of the strip-shaped positive electrode plate 11 in the longitudinal direction (from the starting end to the terminal end in the winding direction of the electrode assembly 14). The negative electrode plate 12 also has a second exposed portion 44, where the negative electrode mixture layer 42 is not provided and the negative electrode core 40 is exposed, at the lower end in the width direction from the winding start end to the winding end end in the longitudinal direction of the strip-shaped negative electrode plate 12 (from the start end to the end end in the winding direction of the electrode body 14). In this embodiment, a case will be described in which the first electrode is the positive electrode plate 11 and the second electrode is the negative electrode plate 12, but the first electrode may be the negative electrode plate 12 and the second electrode may be the positive electrode plate 11.

[0014] The non-aqueous electrolyte has lithium ion conductivity. The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. Examples of the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these. The non-aqueous solvent may contain a halogen-substituted compound (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. The electrolyte salt may include, for example, LiPF ６ Lithium salts such as

[0015] The positive electrode plate 11 includes a positive electrode core 30 and a positive electrode mixture layer 32 formed on both sides of the positive electrode core 30. The positive electrode core 30 can be made of a metal foil, such as aluminum or an aluminum alloy, that is stable within the potential range of the positive electrode plate 11, or a film with such a metal disposed on the surface. The positive electrode mixture layer 32 includes a positive electrode active material, a conductive agent, and a binder. The positive electrode plate 11 can be produced, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, and the like onto the positive electrode core 30, drying the coating, and then compressing it to form the positive electrode mixture layer 32 on both sides of the positive electrode core 30. The positive electrode mixture layer 32 may be formed on only one side of the positive electrode core 30.

[0016] The positive electrode active material is mainly composed of a lithium-containing metal composite oxide. Examples of metal elements contained in the lithium-containing metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, and W. An example of a preferred lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0017] Examples of the conductive agent contained in the positive electrode mixture layer 32 include carbon materials such as carbon black, acetylene black, ketjen black, and graphite. Examples of the binder contained in the positive electrode mixture layer 32 include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resin, acrylic resin, and polyolefin resin. These resins may be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or a salt thereof, polyethylene oxide (PEO), or the like.

[0018] The negative electrode plate 12 has a negative electrode core 40 and a negative electrode mixture layer 42 formed on both sides of the negative electrode core 40. The negative electrode core 40 can be made of a metal foil, such as copper or a copper alloy, that is stable within the potential range of the negative electrode plate 12, or a film with such a metal disposed on the surface. The negative electrode mixture layer 42 contains a negative electrode active material and a binder. The negative electrode plate 12 can be produced, for example, by applying a negative electrode mixture slurry containing a negative electrode active material and a binder to the negative electrode core 40, drying the coating, and then compressing it to form the negative electrode mixture layer 42 on both sides of the negative electrode core 40. The negative electrode mixture layer 42 may be formed on only one side of the negative electrode core 40.

[0019] The negative electrode active material generally uses a carbon material that reversibly absorbs and releases lithium ions. Preferred carbon materials include natural graphite such as flake graphite, lump graphite, and amorphous graphite, and artificial graphite such as lump artificial graphite and graphitized mesophase carbon microbeads. The negative electrode mixture layer 42 may contain a silicon (Si) material as the negative electrode active material. Furthermore, the negative electrode active material may include a metal other than Si that alloys with lithium, an alloy containing such a metal, or a compound containing such a metal.

[0020] As in the case of the positive electrode plate 11, fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, or the like may be used as the binder contained in the negative electrode mixture layer 42, but styrene-butadiene rubber (SBR) or a modified product thereof is preferably used. The negative electrode mixture layer 42 may contain, in addition to SBR or the like, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, or the like.

[0021] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric. Preferred materials for the separator 13 include polyolefin resins such as polyethylene and polypropylene, and cellulose. The separator 13 may have either a single-layer structure or a laminated structure. A heat-resistant layer or the like may be formed on the surface of the separator 13.

[0022] The energy storage device 10 has a metal negative current collector 17 made of nickel, a nickel alloy, or the like, on the axially lower side of the electrode body 14. A second exposed portion 44 protruding from the electrode body 14 is joined to the upper surface of the negative current collector 17, and the negative current collector 17 is joined to the inner surface of the bottom plate of the outer can 15. In other words, the outer can 15, which is electrically connected to the second exposed portion 44 via the negative current collector 17, serves as the negative terminal. By joining the second exposed portion 44 to the negative current collector 17, the contact area can be increased, making it easier to achieve low resistance in the energy storage device 10.

[0023] The energy storage device 10 has a metallic positive current collector 18 made of aluminum, aluminum alloy, or the like, above the electrode body 14 in the axial direction. A first exposed portion 34 protruding from the electrode body 14 is joined to the underside of the positive current collector 18. Joining the first exposed portion 34 to the positive current collector 18 makes it easier to achieve low resistance in the energy storage device 10. The energy storage device 10 has an annular insulating plate 19 above the positive current collector 18 in the axial direction.

[0024] The energy storage device 10 further includes a positive electrode lead 20 made of a metal such as aluminum or an aluminum alloy. The lower end of the positive electrode lead 20 is joined to the upper surface of the positive electrode current collector plate 18 by welding or the like. The positive electrode lead 20 passes through a through-hole in the insulating plate 19 and extends toward the sealing body 16, and the upper end of the positive electrode lead 20 is connected to the lower surface of the filter 22 of the sealing body 16 by welding or the like. A cap 26 that forms the top plate of the sealing body 16 is electrically connected to the filter 22, and the cap 26 serves as a positive electrode terminal.

[0025] The outer can 15 is a cylindrical metal container with a bottom and an open axial end, and the opening of the outer can 15 is closed by a sealing body 16 .

[0026] A gasket 27 is provided between the exterior can 15 and the sealing body 16 to ensure airtightness inside the battery. The exterior can 15 has a grooved portion 21 formed inward on its side surface to support the sealing body 16. The grooved portion 21 is preferably formed in an annular shape along the circumferential direction of the exterior can 15, and supports the sealing body 16 on its top surface. The sealing body 16 is fixed to the top of the exterior can 15 by the grooved portion 21 and the open end of the exterior can 15, which is crimped to the sealing body 16.

[0027] The sealing body 16 has a structure in which, in order from the electrode body 14 side, a filter 22, a lower valve body 23, an insulating member 24, an upper valve body 25, and a cap 26 are stacked. Each member constituting the sealing body 16 has, for example, a disk or ring shape, and each member except for the insulating member 24 is electrically connected to one another. The filter 22 has at least one through-hole. The lower valve body 23 and the upper valve body 25 are connected at their respective centers, with the insulating member 24 interposed between their respective peripheral edges.

[0028] When the power storage device 10 generates abnormal heat and the internal pressure of the power storage device 10 rises, the lower valve body 23 deforms and ruptures, pushing the upper valve body 25 toward the cap 26, and the current path between the lower valve body 23 and the upper valve body 25 is interrupted. If the internal pressure rises further, the upper valve body 25 ruptures, and gas is discharged from the through-hole 26A of the cap 26. This gas discharge prevents the internal pressure of the power storage device 10 from rising excessively, which could cause the power storage device 10 to burst, thereby improving the safety of the power storage device 10.

[0029] [First Exposed Portion] The first exposed portion 34 will be described with reference to FIGS. 2 and 3. FIG.

[0030] In the following, the explanation may be made in accordance with the winding direction of the electrode body 14 (arrow α in FIG. 2), the winding axis direction of the electrode body 14 (arrow β in FIG. 2), and the winding radial direction of the electrode body 14 (arrow γ in FIG. 3). Ｆ ) or the end of the winding (arrow α in Figure 2 Ｅ ) may be explained.

[0031] As described above, the first exposed portion 34 is a portion where the positive electrode mixture layer 32 of the positive electrode plate 11 is not provided and the positive electrode core 30 is exposed. As shown in FIG. 2 with the positive electrode plate 11 in an unfolded state, the first exposed portion 34 has multiple notches 34A. The notches 34A are formed at a predetermined angle θ with respect to the winding axis direction. As illustrated in FIG. 2 , the notches 34A may be formed at a predetermined angle θ with respect to the winding axis direction so as to tilt toward the winding start side. In other words, when the notches 34A have a first end on the edge side of the first exposed portion 34 and a second end on the positive electrode mixture layer 32 side in the width direction of the positive electrode plate 11, the second end of the first exposed portion 34 is located closer to the end in the winding direction than the first end. When the width dimensions of the notches 34A are different, the first end and the second end may be the portions of the first exposed portion 34 closest to the start end in the winding direction. The notches 34A may also be formed at a predetermined angle θ toward the end of the winding relative to the winding axis. The predetermined angle θ is 10° or greater, and preferably 30° or greater. In particular, by setting θ within the range of 60° to 70°, axial dimensional variations among the strips 34B arranged in the radial direction can be suppressed. Strips 34B with an inappropriate θ tend to have a small amount of axial protrusion of the inner strips 34B in the wound electrode body 14.

[0032] The multiple cuts 34A are formed to be parallel to one another. However, the multiple cuts 34A of the present disclosure do not have to be parallel to one another. The intervals between the multiple cuts 34A in the winding axis direction are substantially uniform. However, the intervals between the multiple cuts 34A in the winding axis direction of the present disclosure may be uneven. Furthermore, the intervals between the cuts 34A in the winding axis direction are preferably shorter than the length of the first exposed portion 34 in the winding axis direction. Furthermore, the cuts 34A are preferably formed at a position at a slight distance from the positive electrode mixture layer 32 at the lower end of the first exposed portion 34 in the winding axis direction.

[0033] Between adjacent cutouts 34A, strips 34B are formed. In other words, in the first exposed portion 34, adjacent cutouts 34A form a plurality of strips 34B. The strips 34B are formed so as to form a parallelogram when viewed from the winding radial direction. In other words, the strips 34B are rectangular, formed by first sides (sides formed by the cutouts 34A) that are parallel to each other and second sides (sides parallel to the winding direction) that are parallel to each other.

[0034] The first side of the strip portion 34B is inclined at a predetermined angle θ with respect to the winding axis direction. Hereinafter, when the first side of the strip portion 34B is inclined at the predetermined angle θ with respect to the winding axis direction, it is simply referred to as the strip portion 34B being inclined at the predetermined angle θ with respect to the winding axis direction. As illustrated in FIG. 2 , the strip portion 34B may be inclined at the predetermined angle θ toward the winding start side with respect to the winding axis direction. Alternatively, the strip portion 34B may be inclined at the predetermined angle θ toward the winding end side with respect to the winding axis direction. It is preferable that the multiple strip portions 34B have substantially the same shape. However, the multiple strip portions 34B of the present disclosure do not have to have substantially the same shape. It is preferable that the strip portion 34B is formed so that the first side is longer than the second side.

[0035] As shown in the wound state of the positive electrode plate 11 in FIG. 3 , the strip portion 34B is folded toward the electrode assembly 14. More specifically, the strip portion 34B is folded inward in the winding radial direction of the electrode assembly 14. As described above, the first side of the strip portion 34B is formed so as to be inclined at a predetermined angle θ with respect to the winding axis direction. Therefore, the strip portion 34B is folded so as to be inclined at the predetermined angle θ with respect to the winding radial direction of the electrode assembly 14. As exemplified in FIG. 3 , the strip portion 34B may be folded so as to be inclined at the predetermined angle θ toward the winding start side with respect to the winding radial direction. Alternatively, the strip portion 34B may be folded so as to be inclined at the predetermined angle θ toward the winding end side with respect to the winding radial direction.

[0036] Furthermore, among the multiple strip portions 34B, the first strip portion and the second strip portion that are adjacent to each other are closer to the end of the first exposed portion 34 than the second strip portion in the winding direction, the first strip portion and the second strip portion are each folded in the radial direction of the electrode body 14, a portion of the first strip portion and a portion of the second strip portion overlap each other in the winding axis direction, and a portion of the second strip portion is located outside (above) in the winding axis direction.With this configuration, the strip portions 34B can be folded efficiently when the folding jig is rolled from the outside to the inside of the electrode body 14 and knocked down.

[0037] In the first exposed portion 34, strip portions 34B are formed between adjacent notches 34A, and a protective layer containing an insulating material is formed on the surface of the strip portions 34B in a region toward the second end, with the region toward the first end being exposed from the protective layer. The strip portions 34B may be folded in the radial direction of the electrode body 14, and the strip portions 34B may be bent in the region where the protective layer is formed. With this configuration, the bending position is lower compared to a configuration in which the strip portions 34B with the protective layer are bent at the portion exposed from the protective layer, and the dimension of the first exposed portion 34 in the winding axis direction after folding can be reduced. The protective layer bent together with the strip portions 34B may overlap adjacent strip portions 34B in the radial direction. At this time, a layer in which a predetermined number or more of the exposed portions (tip portions) of the strip portions 34B without the protective layer are overlapped in the width direction of the positive electrode plate 11 is disposed axially on the outer side (upper side) of the electrode body 14 relative to the portion extending radially from the bending point of the protective layer and the adjacent strip portions 34B. In other words, the portion extending radially from the bending point of the protective layer is disposed between this overlapping layer and the positive electrode and negative electrode mixture layers. This configuration allows for more reliable welding of the first exposed portion 34 and the positive electrode current collector plate 18. The protective layer may be composed of a mixture of a binder and inorganic particles such as a metal oxide.

[0038] Furthermore, the first exposed portion 34 may be folded in the same direction as the strip portions 34B formed in the area excluding the outermost periphery of the same first exposed portion 34, with no notches 34A formed in the portion corresponding to the outermost periphery of the electrode body 14. This configuration makes it possible to hold down the strip portions 34B without notches, and makes it possible to prevent the strip portions 34B from warping outward from the electrode body 14, compared to a configuration in which the strip portions 34B are provided in the outermost periphery.

[0039] [Second Exposed Portion] As described above, the second exposed portion 44 is a portion where the negative electrode mixture layer 42 of the negative electrode plate 12 is not provided and the negative electrode core 40 is exposed. A plurality of cut portions are formed in the second exposed portion 44. The cut portions are similar to the cut portions 34A of the first exposed portion 34 described above, and therefore a description thereof will be omitted. Furthermore, strip portions are formed between adjacent cut portions. The strip portions are similar to the strip portions 34B of the first exposed portion 34 described above, and therefore a description thereof will be omitted. Furthermore, the strip portions are folded toward the electrode body 14.

[0040] Other Embodiments In the above-described embodiment, a notch is formed in both the first exposed portion 34 and the second exposed portion 44, a strip portion is formed, and the strip portion is folded onto the electrode body 14. However, the present disclosure may also be configured such that a notch is formed in only one of the first exposed portion 34 or the second exposed portion 44, a strip portion is formed, and the strip portion is folded onto the electrode body 14.

[0041] [Manufacturing Process of the Power Storage Device] A manufacturing process of the power storage device 10, which is an example of an embodiment, will be described with reference to FIGS. 4 to 6. FIG.

[0042] 4, the manufacturing process of the energy storage device 10 includes a positive electrode plate forming step S11, a negative electrode plate forming step S12, a cutting step S13, a winding step S14, and a folding step S15, each of which will be described in detail later. Note that a description of the other steps in the manufacturing process of the energy storage device 10 will be omitted.

[0043] In the positive electrode plate formation step S11, a positive electrode mixture layer 32 is formed on both sides of the positive electrode core 30, and a first exposed portion 34 is formed on both sides of the upper end portion of the positive electrode core 30. The positive electrode core 30 is preferably cut out so that the portion where the first exposed portion 34 is to be formed has a parallelogram shape.

[0044] In the negative electrode plate formation step S12, a negative electrode mixture layer 42 is formed on both sides of the negative electrode core 40, and a second exposed portion 44 is formed on both sides of the lower end portion of the negative electrode core 40. The negative electrode core 40 is preferably cut out so that the portion where the second exposed portion 44 is to be formed has a parallelogram shape.

[0045] In the cutting step S13, multiple cuts 34A are formed in the first exposed portion 34. As described above, the cuts 34A are formed at a predetermined angle θ with respect to the winding axis direction. As a result, strips 34B are formed between adjacent cuts 34A. Multiple cuts are formed in the second exposed portion 44 in the same way as in the first exposed portion 34. Note that examples of means for forming these cuts include a laser and a mold.

[0046] In the winding step S14, the positive electrode plate 11 and the negative electrode plate 12 are wound with the separator 13 interposed therebetween. At this time, the strip portions 34B of the first exposed portion 34 formed in the cutting step S13 are inclined at a predetermined angle θ with respect to the winding axis direction and protrude upward in the winding axis direction. On the other hand, the strip portions of the second exposed portion 44 are inclined at the predetermined angle θ with respect to the winding axis direction and protrude downward in the winding axis direction.

[0047] In the folding step S15 , the folding jig 50 presses down the strip portions 34B, and the strip portions 34B are folded toward the electrode body 14 .

[0048] As shown in FIG. 5 , the folding jig 50 is a so-called ball bearing. The folding jig 50 includes a first sphere 51 and a plurality of second spheres (not shown), each of which will be described in detail below. The first sphere 51 is a member that pushes down the strip portion 34B. The second spheres are members that support the first sphere 51 so that it can rotate freely and have a smaller diameter than the first sphere 51. The folding jig 50 allows the first sphere 51 to rotate smoothly. In addition to using the second spheres as a means for rolling the first sphere 51 within the folding jig 50, this can also be achieved by supporting the first sphere 51 on a support having a recess with a curved surface that follows the spherical surface of the first sphere 51.

[0049] In the folding step S15, the first spherical body 51 of the folding jig 50 can push down the strip portions 34B while smoothly rotating. This allows the strip portions 34B to be folded while fitting together. As a result, the rigidity of the strip portions 34B makes the strip portions 34B less likely to rebound.

[0050] Furthermore, the strip portions 34B can be folded with low friction. This reduces the generation of metallic foreign matter when folding the strip portions 34B. Furthermore, the positive electrode mixture layer 32 is less likely to peel off. Furthermore, the generation of wrinkles after folding the strip portions 34B can be suppressed.

[0051] The folding jig 50 is supported by a moving device (not shown) that moves the folding jig 50 at least in the winding radial direction. This allows the folding jig 50 to be freely moved in the winding radial direction. The electrode body 14 is supported by a rotating device 63. This allows the electrode body 14 to be freely rotated. The folding jig 50 may be moved not only in the radial direction but also in the axial direction. In particular, when moving the folding jig 50 on the inner side of the electrode body 14, it may be moved to a position farther away from the electrode body 14 in the axial direction than when moving the folding jig on the outer side. This method allows the inner side strips 34B, which are more likely to be folded so that their bending points are lower than those of the outer side, to be bent at a higher position. This also reduces the variation in the amount of axial protrusion between the outer side strips 34B and the inner side strips 34B.

[0052] 6, in the folding step S15, the folding jig 50 is moved from the outside to the inside in the winding radial direction while the electrode body 14 is rotated by the rotation device 60. As a result, the folding jig 50 moves in a spiral shape from the outside to the inside in the winding radial direction on the upper end surface of the electrode body 14 (arrow R in FIG. 6).

[0053] As described above, the strip portions 34B are formed at a predetermined angle θ with respect to the winding axis direction. This reduces the angle between the movement path of the folding jig 50 and the longitudinal direction of the folded strip portions 34B. In other words, the movement path of the folding jig 50 is aligned with the folding direction of the strip portions 34B. This makes it easier to fold the strip portions 34B. As a result, the folded height of the strip portions 34B (the length of the folded strip portions 34B in the winding axis direction) can be reduced. This increases the proportion of the positive electrode mixture layer 32 in the electrode body 14. As a result, the capacity of the energy storage device 10 can be increased.

[0054] On the other hand, for example, if the strip portions 34B are formed along the winding axis direction and the electrode body 14 is rotated and the folding jig 50 is moved from the outside to the inside in the winding radial direction, the angle between the movement path of the folding jig 50 and the longitudinal direction of the folded strip portions 34B is large. In this case, the strip portions 34B are difficult to fold. As a result, the folding height of the strip portions 34B cannot be reduced.

[0055] In the folding step S15, if the strip portions 34B are formed so as to be inclined at a predetermined angle θ toward the winding start side with respect to the winding radial direction, the folding jig 50 is moved from the outside toward the inside in the winding radial direction while the electrode body 14 is rotated toward the winding end side. As a result, while the electrode body 14 is rotating, the folding jig 50 moves from the base end side toward the tip end side in the longitudinal direction of the strip portions 34B. As a result, the strip portions 34B are folded.

[0056] On the other hand, when the strip portions 34B are formed so as to be inclined at a predetermined angle θ toward the winding end side with respect to the winding radial direction, the folding jig 50 is moved from the outside toward the inside in the winding radial direction while rotating the electrode body 14 toward the winding start side. As a result, while the electrode body 14 is rotating, the folding jig 50 moves from the base end side toward the tip end side in the longitudinal direction of the strip portions 34B. As a result, the strip portions 34B are folded.

[0057] In the folding step S15, the electrode body 14 may be fixed, and the folding jig 50 may be moved spirally by a moving device. In addition, in the folding step S15, the electrode body 14 may be fixed, and the folding jig 50 may be moved sequentially along the long sides of the strip portions 34B by a moving device.

[0058] In addition, in the folding step S15 described above, folding of the first exposed portion 34 has been described, but the same applies to folding of the second exposed portion 44.

[0059] [Summary] The present disclosure is further described by the following embodiments. Configuration 1: An energy storage device including an electrode body formed by winding a first electrode plate and a second electrode plate with a separator interposed therebetween, wherein the first electrode plate includes a first core, a first mixture layer formed on the surface of the first core, and a first exposed portion where the first core is exposed, wherein the exposed portion is provided at one end of the electrode body in the winding axis direction, and wherein the first exposed portion has a plurality of cut portions formed in the first exposed portion and aligned in the winding direction of the electrode body, wherein the cut portions each have a first end on an edge side of the first exposed portion and a second end on the first mixture layer side, and are formed at an angle inclined by a predetermined angle in the winding axis direction, and wherein the second end of the first exposed portion is closer to the end of the first exposed portion than the first end in the winding direction. Configuration 2: The energy storage device according to configuration 1, wherein a strip portion is formed between adjacent cut portions. Configuration 3: The energy storage device according to configuration 2, wherein the strip portion is a parallelogram when viewed from the winding radial direction.Configuration 4: The energy storage device according to configuration 3, wherein the strip portion is folded toward the electrode body.Configuration 5: The energy storage device according to any one of configurations 1 to 4, wherein the predetermined angle is 10 degrees or more. Configuration 6: The energy storage device according to Configuration 1, wherein a strip portion is formed between adjacent ones of the plurality of cut portions in the first exposed portion, and among the plurality of cut portions, a first strip portion and a second strip portion are adjacent to each other in the winding direction, and in the winding direction, the first strip portion is closer to an end of the first exposed portion than the second strip portion, and the first strip portion and the second strip portion are each folded in a radial direction of the electrode body, and a portion of the first strip portion and a portion of the second strip portion overlap each other in the winding axis direction, and a portion of the second strip portion is located outward in the winding axis direction than a portion of the first strip portion.Configuration 7: The energy storage device according to Configuration 1, wherein strip portions are formed between adjacent cut portions in the first exposed portion, a protective layer containing an insulating material is formed on the surface of the strip portions in a region on the second end side, and the region on the first end side is exposed from the protective layer, the strip portions are folded in a radial direction of the electrode body, and the strip portions are bent in the region where the protective layer is formed. Configuration 8: A method for manufacturing an electricity storage device comprising an electrode body formed by winding a first electrode plate and a second electrode plate with a separator interposed therebetween, the first electrode plate including a first core and a first mixture layer formed on the surface of the first core, a first exposed portion where the first core is exposed is provided at one end of the electrode body in the direction of the winding axis, a plurality of notches are formed in the first exposed portion, the notches are formed at a predetermined angle with respect to the winding axis direction, strip portions are formed between adjacent notches, and the strip portions are folded toward the electrode body, wherein when the strip portions are folded, the strip portions are pushed down by a folding jig, and the folding jig comprises a first sphere that pushes down the strip portions. Configuration 9: A method for manufacturing an electricity storage device according to Configuration 8, wherein the folding jig further comprises a second sphere that rotatably supports the first sphere and has a diameter smaller than the first sphere. Configuration 10: The method for manufacturing an electric storage device according to Configuration 8, wherein, when folding the strip portions, the electrode body is rotated along the winding axis direction and the sphere is moved along the winding radial direction. Configuration 11: The method for manufacturing an electric storage device according to Configuration 10, wherein, when the cut portions are inclined so as to fall toward the winding end side with respect to the winding axis direction, the electrode body is rotated toward the winding start side, and when the cut portions are inclined so as to fall toward the winding start side with respect to the winding axis direction, the electrode body is rotated toward the winding end side.

[0060] It should be noted that the present disclosure is not limited to the above-described embodiments and their variations, and it goes without saying that various modifications and improvements are possible within the scope of the matters described in the claims of the present application.

[0061] REFERENCE SIGNS LIST 10 Energy storage device, 11 Positive electrode plate (first electrode plate), 12 Negative electrode plate (second electrode plate), 13 Separator, 14 Electrode body, 15 Outer can, 16 Sealing body, 17 Negative electrode current collector plate, 18 Positive electrode current collector plate, 19 Insulating plate, 20 Positive electrode lead, 21 Grooved portion, 22 Filter, 23 Lower valve body, 24 Insulating member, 25 Upper valve body, 26 Cap, 26A Through hole, 27 Gasket, 30 Positive electrode core (first core body), 32 Positive electrode mixture layer (first mixture layer), 34 First exposed portion, 34A Cut portion, 34B Strip portion, 40 Negative electrode core, 42 Negative electrode mixture layer, 44 Second exposed portion, 50 Folding jig, 51 First sphere, 60 Rotating device, S11 Positive electrode plate forming step, S12 negative electrode plate forming step, S13 cutting step, S14 winding step, S15 folding step

Claims

1. An energy storage device comprising an electrode body in which a first electrode plate and a second electrode plate are wound with a separator interposed therebetween, the first electrode plate including a first core, a first mixture layer formed on the surface of the first core, and a first exposed portion where the first core is exposed, the first exposed portion being provided at one end of the electrode body in the winding axis direction, the first exposed portion having a plurality of notches lined up in the winding direction of the electrode body, the notches each having a first end on the edge side of the first exposed portion and a second end on the first mixture layer side, and being formed at an angle inclined in the winding axis direction, and the second end of the first exposed portion being closer to the end of the first exposed portion than the first end in the winding direction.

2. The electricity storage device according to claim 1, wherein a strip portion is formed between adjacent cut portions.

3. The energy storage device according to claim 2, wherein the rectangular portion is a parallelogram when viewed in the radial direction of the winding.

4. The electricity storage device according to claim 3, wherein the strip portion is folded toward the electrode body.

5. The electricity storage device according to any one of claims 1 to 4, wherein the predetermined angle is 10° or more.

6. An energy storage device according to claim 1, wherein a strip portion is formed between adjacent ones of the plurality of cut portions in the first exposed portion, and among the plurality of cut portions, a first strip portion and a second strip portion are adjacent to each other in the winding direction, and in the winding direction, the first strip portion is closer to an end of the first exposed portion than the second strip portion, and the first strip portion and the second strip portion are each folded in the radial direction of the electrode body, and a portion of the first strip portion and a portion of the second strip portion overlap each other in the winding axis direction, and a portion of the second strip portion is located outward in the winding axis direction than a portion of the first strip portion.

7. An energy storage device according to claim 1, wherein strip portions are formed between adjacent cut portions in the first exposed portion, a protective layer containing an insulating material is formed on the surface of the strip portions in an area on the second end side, and the area on the first end side is exposed from the protective layer, the strip portions are folded in the radial direction of the electrode body, and the strip portions are bent in the area where the protective layer is formed.

8. A method for manufacturing an electricity storage device comprising an electrode body in which a first electrode plate and a second electrode plate are wound with a separator interposed therebetween, the first electrode plate including a first core and a first mixture layer formed on the surface of the first core, a first exposed portion where the first core is exposed is provided at one end of the electrode body in the direction of the winding axis, a plurality of notches are formed in the first exposed portion, the notches are formed at an inclination of a predetermined angle with respect to the direction of the winding axis, strip portions are formed between adjacent notches, and the strip portions are folded towards the electrode body, wherein when the strip portions are folded, the strip portions are pushed down by a folding jig, and the folding jig has a first sphere that pushes down the strip portions.

9. A method for manufacturing an electric storage device according to claim 8, wherein the folding jig further comprises a second sphere having a smaller diameter than the first sphere and supporting the first sphere so as to be rotatable.

10. A method for manufacturing an electric storage device according to claim 9, wherein when folding the strip portion, the electrode body is rotated along the winding axis direction, and the folding jig is moved along the winding radial direction.

11. A method for manufacturing an electric storage device as defined in claim 10, wherein when the notch is inclined so as to fall towards the end of winding with respect to the direction of the winding axis, the electrode body is rotated towards the start of winding, and when the notch is inclined so as to fall towards the start of winding with respect to the direction of the winding axis, the electrode body is rotated towards the end of winding.

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